In recent years, the development of organic EL display devices is progressing with the goal of achieving thinner display panels, high luminosity and high speed. An organic EL display device is a display device arranged with pixels structured from organic light emitting diodes. Since the reaction speed is fast because there are no mechanical operations and each pixel itself emits light, in addition to being able to display at high luminosity, because a thin panel is possible due to the lack of a need for a backlight, the next generation of display devices are anticipated.
FIG. 1 is a vertical cross-sectional diagram showing an example of a stacked structure of an organic EL display device 10. As is shown in FIG. 1, an organic EL light emitting layer 1 is formed above a hard substrate 2 such as glass. Although a detailed depiction is omitted in FIG. 1, the organic EL light emitting layer 1 may be formed by stacking a TFT (Thin Film Transistor), a drive circuit layer, a reflection electrode, a hole injection layer, a hole transport layer, an electrode transport layer, a hole injection layer, a transparent electrode in this order from the substrate 2 side.
The organic EL light emitting layer 1 degrades rapidly when exposed to the water component within the atmosphere, it is necessary to seal the layer from outside air. Thus, as is shown in FIG. 1, the surface of the organic EL light emitting layer 1 is covered by a transparent sealing film 3 comprised from a CVD formed silicon nitride (SIN) film for example. In addition, the surface of the sealing film 3 is sometimes covered by a transparent resin 4, 5. A substrate 7 formed with the organic EL layer 1 and sealing film 3 shown in FIG. 1 is referred to as [first substrate 7] below. The organic EL display device 10 is formed by adhering an opposing substrate 6 comprising from a hard transparent component such as glass via the resin 4, 5 above the first substrate 7.
The organic EL display device 10 arranged with this type of structure is arranged with a display part 12 arranged with a plurality of pixels including the organic EL light emitting layer 1, the display part being a region for displaying an image, and a terminal part 13 which is a region arranged with a plurality of terminals 13a which carry out an electrical connection with an exterior circuit. FIG. 2 is a perspective view showing an approximate structure of the organic EL display device 10 and shows the structure of the first substrate 7 arranged with the display part 12 and terminal part 13, and the structure of a second substrate 8 and third substrate 9 arranged facing the first substrate 7. Here, the second substrate 8 and third substrate 9 shown in FIG. 2 correspond to the opposing substrate 6 shown in FIG. 1. The opposing substrate 6 is not limited to the structure shown in the diagram and may also be formed including a plurality of other substrates according to the specifications of the organic EL display device 10. The second substrate 8 may be a color filter substrate arranged with a color filter formed corresponding to each pixel. The third substrate 9 may be a touch panel arranged with a sensor device etc including a touch panel function.
As is shown in FIG. 2, in the terminal part 13, the plurality of terminals 13a are formed exposed without being covered by the opposing substrate 6 including the sealing film 3, resin 4, 5 and second substrate 8 and third substrate 9 shown in FIG. 1. The parts of the plurality of terminals 13a which are exposed are connected to an external circuit for supplying a drive signal such as a FPC (Flexible Printed Circuit) substrate. In addition, the plurality of terminals 13a is connected to the organic EL light emitting layer 1 via wiring etc formed above the substrate 2.
In this way, in the manufacturing process of the organic EL display device 10, in the case where the sealing film 3 which covers the organic EL light emitting layer 1 is formed covering the entire surface of the substrate 2, it is necessary to perform a process (also referred to below as [terminal extraction]) for exposing the plurality of terminals 13a from the sealing film 3.
A conventional method is known in which after forming the sealing film 3 above the terminal part 13, the sealing film 3 above the terminal part 3 is removed using tape peeling or etching (dry or wet) as a method for exposing the plurality of terminals 13a. In the case of removing the sealing film 3 above the terminal part 13 using etching, etching is performed after the first substrate 7 and second substrate 8 are bonded together. In this way, because the second substrate 8 itself apart from the terminal part 13 becomes a hard mask, it is possible to remove the sealing film 3 above the terminal part 13 without etching the sealing film 3 of the display part 12.
Here, for example 5 μm or less of a SiN film or 1 μm of an acryl stacked film (for example, SiN/organic resin film (acryl)/SiN, SiN/SiO (or a/Si)/organic resin film (acryl)/SiN) is sometimes used for the sealing film 3. When an etching process is performed using a plasma on the sealing film 3 comprising this type of SiN film or acryl stacked film, there is a danger that the organic EL light emitting layer 1 formed in the first substrate 7 is damaged due to heat. For example, when the temperature of the first substrate 7 rises above 100° C., degradation or crystallization occurs in the organic EL material included in the organic EL light emitting layer 1 and there was a danger that reliability of the organic EL display device 10 would be lost.
In order to reduce the effects on a display device due to this heat, a structure in which a heat sink comprised from a line shaped or mesh shaped metal material is arranged between a light emitting panel and a diffusion plate for example was used in a conventional display device (for example, refer to patent document 1 [Japanese Laid Open Patent 2007-328339]).
However, in the case of a structure in which a heat sink is arranged on the side of a light emitting panel as in the conventional display device described above, there was a danger that the effects of heat on the organic EL light emitting layer 1 due to a heat sink could not be reduced. That is, in the case of performed a terminal extraction process by removing the sealing film 3 formed in the first substrate 7 corresponding to a light emitting panel by etching, there was a danger that heat would be transmitted to the organic EL light emitting layer 1 via the second substrate 8 due to performing an etching process from the side of the adhered second substrate 8.
In addition, in the case of not using this type of etching method, for example, removing the sealing layer 3 covering the terminal part 13 by a peeling method, there was a danger that the peeling interface would not be uniform leaving peeling behind. In addition, in the case of forming the sealing film 3 which does not cover the terminal part 13 using a mask, because a separate process is necessary for cleaning the mask and a high level of accuracy is demanded for positioning, there was a danger that the manufacturing process becomes complex and yield decreases.